Circuit control switch means with axially adjustable cam

ABSTRACT

Can and switch means for control of circuits, such that, on setting or aligning the cam relative to a point on a scale, a switch member will be rotated to change the position thereof, relative to the cam, to actuate the switch at the set scale point, and thus control a circuit. The cam is adjustable along its axial dimension so that if one portion of it is worn, a new portion can be brought into contact with the cam follower without changing the cam.

United States Patent [72] Inventor William E. Engelhard Apalachin, N.Y. [21] Appl. No. 727,509 [22] Filed May 8, 1968 [45] Patented July 6, 1971 [73] Assignee Pym-Sew Instruments, Inc.

' North Arlington, NJ.

[54] CIRCUIT CONTROL SWITCH MEANS WITH AXIALLY ADJUSTABLE CAM 4 Claims, 7 Drawing Figs.

[52] US. Cl 200/153, 74/568, 200/31, 200/38 [51] Int. Cl H01h-3/42, I-10lh 19/62 [50] Field of Search 74/568, 569; ZOO/153.13, 153.1 1, 153.19, 166 M, 31, 22, 38 B, 38 C, 153.12; 123/90 [56] References Cited UNITED STATES PATENTS 2,213,994 9/1940 Rankin 74/568 2,277,153 3/1942 Scottet a1 74/568 2,469,570 5/1949 Parish 74/568 X Primary Examiner-Robert K. Schaefer Assistant Examiner-Robert A. Vanderhye Attorney-Sommers and Sommers ABSTRACT: Can and switch means for control of circuits,

such that, on setting or aligning the cam relative to av oint onv a scale, a switch member will be rotated to change the position thereof, relative to the cam, to actuate the switch at the set scale point, and thus control a circuit. The cam is adjustable along its axial dimension so that if one portion of it is worn, a new portion can be brought into contact with the cam follower without changing the cam.

PATENTEU JUL 5 IHTI SHEET 1 BF 2 FIG.

INVENTOR 14 E. ENGELHARD ATTORNEYS PATENTEDJUL am 3.591.746

sum 2 0F 2 INVENTOR W. E. ENGELHARD ATTORNEYS CIRCUIT common. swircii MEANS wmi AXIALLY ADJUSTABLE CAM CIRCUIT CONTROL SWITCH MEANS This invention relates to switches for control of circuits, for example, to provide on-off control of furnaces, cyrogenic equipment and other apparatus or circuits wherein increments (whether thennal or otherwise, for example, linear-such as for time lapse or other indication) may be indicated by points on a scale, and wherein it is desired that the switch shall effectuate (open or close) an electrical circuit on occurrence of a predetermined control scale reading.

The invention provides means for precisely controlling onoff circuit cycles by providing novel and efficient switch means for the purpose, including a cam member which may be set, on movement of a control knob, to locate a critical cam area (such as a recessed transverse portion on the cam) at such point as will actuate the switch automatically, accurately and without error on registration of a switch element therewith, for example, when the circuit has been on sufficiently long to move the switch to the registration position for which a control knob has been set.

Pursuant to the invention, the cam is formed relatively wide, to provide an extended width for adjustment of the position of the switch actuator arm or button, so that, on wear or damage to a particular point or critical area of the cam (such as a recessed portion on the cam to receive the arm or button of the switch, and thus actuate the switch) the switch may be moved to locate the arm or button thereof for registration ofa fresh, undamaged surface of the critical cam area, thus enhancing the accuracy of the device.

The invention enables utilization of a minimum number of parts, which may be simply and accurately mounted for achievement of the stated objectives, in a compact, efficient control instrument, minimizing the likelihood of error due to misalignment, play, friction, difficulty of adjustment, and other objections to devices heretofore proposed for the purpose.

The accompanying drawings illustrate procedures and devices useful in carrying out the invention, which shall be deemed to cover all other devices and procedures coming within the scope and purview of the appended claims.

In the drawings, wherein similar reference characters indicate like parts:

FIG. 1 is a front elevational view of a circuit control instrument embodying the invention,

FIG. 2 is an exploded, partly fragmentary view of parts thereof, taken at line 2--2 of FIG. I,

FIG. 3 is a fragmentary, elevational view, showing a means which may be used in carrying out the invention, for adjusting the position of the switch actuator pin or button, to compensate for wear and tear, on the critical cam area 17,

FIG. 4 is a similar view of another means which may be used in carrying out the invention,

FIG. 5 is a fragmentary, perspective view of parts of a device embodying the invention,

FIG. 6 is an enlarged, fragmentary, elevational view of a second pointer, 32, micro switch 20, and its actuator button and cam I6 for actuating the microswitch, which may be used in carrying out the invention, taken at line 6-6 of FIG. 2, and

FIG. 7 is a fragmentary, exploded view of cam and control knob parts which may be used in carrying out the invention.

As shown in the drawings, the device of this invention comprises a circuit control instrument I0, having a casing with an opening II, for viewing, a scale 13, which may be marked on a panel 12 in said instrument I0 and thus visible at (FIG. I) the front of the instrument. Panel 12 may be wholly or partly light permeable and scale 13 may be suitably inscribed or (FIG. 3)

marked with desired degree or other measurement indicia. The scale and the (below mentioned) pointer or pointers, may be formed translucent or transparent and aligned in such relation to each other as may be found convenient for the purpose of the invention as set forth herein and in the drawings.

The first pointer 1 may (FIG. 2) be fixed, in any desired or convenient manner, to pointer setting knob 15 (which may be formed of more than one part, for facility of manufacture and installation) and which has fixed thereto or formed unitarily therewith the cam 16 (FIGS. 6, 7) provided with critical cam area or undulation 17, which may be in the form of a transverse recessed portion to receive the microswitch pin or button 23, to thereby control a circuit such as a heating or cooling circuit. Said circuit may be closed (or open) until the microswitch button 23 is so received in the critical cam area 17.

In the form shown in the drawings (by way of example only) the knob 15 is rotated (manually or by motor or other automatic means) to set" the knob at the position at which it or the pointer 14 registers with the scale marking desired. Thereupon the microswitch will have to be rotated to a degree so predetermined to achieve the circuit cutoff (or on) point on the scale on registration of microswitch button 23 with the critical cam area or undulation 17. Thus the furnace heating circuit, (or cyrogenic cooling circuit) for example, will continue closed (or open) until such registration of parts 23 and 17. The circuit may be one which will be open until parts 23 and 37 so register, for particular applications, as will be apparent to those skilled in this art.

The setting pointer 14 is secured to the shaft or control knob 15 which rotatably passes through, and is suitably journaled in (FIG. 2) an opening in, the lower wall 10 a of casing 10.

Setting of the instrument is achieved by the users rotating knob 15 to register the setting pointer 14 with the particular desired (thus selected) degree reading on scale 13. Cam plate 16 extends as a ring or ledge portion (FIG. 7) of knob shaft 15 for a purpose below explained. A bearing, such as ring or tube 19 (FIG. 2) is fixed, as at 21, to casing 10 and extends preferably coaxially with armature shaft 24 for cooperation of the antifriction means 26 of the armature shaft therewith, as below described.

The motor casing 25 is rotatably journaled in the instrument housing 10 in any desired or convenient manner, so as to axially dispose the armature shaft end of the motor casing 25 in alignment with the bearing 19 as below set forth. The motor casing barrel 25 may have fixed thereto the field of the motor and may have fixed to and extending rearwardly therefrom stub shaft 22 (FIG. 5) said stub shaft being and freely rotatably journaled in a bearing 34 which may, in turn, be fixed or keyed to the instrument housing 10 in any desired or convenient manner.

Microswitch 20, having a movable switch actuator pin 23 for registration with a critical control knob cam area (such as 17, FIG. 6) is secured (as at 42, FIGS. 2, 5) to the motor casing 25 or to bracket 30 fixed to casing 25.

Switch 20 is preferably a microswitch which operates, for example, on 0.002 of an inch differential; it is therefore imperative to avoid any wear or effects of wear; the device of the invention reduces wear to an absolute minimum and provides means for compensating for wear. Cam plate 16 has a critical cam area-for example, which may e a depressed or recessed area 17 (extending the width of cam plate 16) which may be heat treated to resist wear. Means may be provided such, that if any particular spot in the critical cam area 17 wears, the complementary switch means 20, engageable therewith, may be shifted to engage a fresh, unworn portion of the critical cam area 17 and thus maintain the accuracy of the device in extended use.

Thus, for example (FIG. 3) bracket 30 may be secured to motor casing 25 by bolt 35 passing through a slot 18 in bracket 30 so that the bracket may be moved axially, and thus carry the microswitch 20 therewith axially to position the microswitch actuator pin or button 23 at the precise location on the cam desiredfor example, beyond a worn surface thereof. In FIGS. 2 and 4, microswitch 20 is shown movable exemplarily illustrated relative to the bracket 30 which is fixed to motor barrel or casing 25. Bolt or bolts 42 (FIGS. 5, 4) pass freely through apertures in second pointer or motor index 32 and flange 40 of bracket 30 and through a complementarily apertured portion 41 in microswitch 20. The scale panel 12 may be mounted in casing 10 rearwardly of pointer or pointers, or forwardly thereof as shown in FIG. 2 by way of example only. The critical area 17 of the cam 16 may by heat treated to resist wear and made wide (FIG. 7) to provide fresh surfaces for contact therewith of the actuator pin 23 of the microswitch as above noted. Thus by rotating bolt r bolts 42, the microswitch and actuator pin or button 23 may be axially moved to position the pin or button 23 at the precise location on the cam desiredfor example, beyond alignment with a worn surface of the cam.

The portion 24 (FIG. 2) of the motor armature extending out of the motor casing or barrel 25, has fixed thereto or to an enlarged end 24 thereof (FIGS. 2, antirotation means such as, for example, O-rings 26, proportioned to be snugly received within bearing 19 (FIG. 2) to thereby normally frictionally hold the rotor against rotation. The O-rings 26 swell out to take up any wear and thus, until completely worn, will always be centered. Bearing I9 is nonrotatably keyed to switch casing 10 as by suitable means such as by stud 21, fixed to the bearing I9 and to the casing 10. The ends 16 (FIG. 7) of the cam may engage the stop 21 so that any tendency of the motor to override would result in slight rotation of armature shaft 24 beyond or against the resistance effect of the antirotation rings 26.

On signal actuation of motor 25 from the source to be controlled, the armature shaft 24 will, (pursuant to the above described construction) be frictionally held stationary, and

the motor barrel or casing 25 will then rotate within a limited arc. Thus not much motion (and wear) will be imparted to the parts pursuant to the invention.

Actuation of motor 25 is achieved in proportion to the pick up control signal, as by wires 37, going through an amplifier and to a thermocouple or other instrument from a furnace, pyrogenic area, or other source or electrical apparatus to be controlled pursuant to the invention. A wiper arm 29 (FIG. 5) on the motor barrel 25 wipes a potentiometer circuit wire 28. Wires 27 are connected with a potentiometer network. Wiper 29 has signal pickup wire 29 secured thereto for connection with the plus of the thermocouple. Wires 33 connect the microswitch 20 with the controls of the furnace or other equipment to be controlled.

The cam operated microswitch may be wired to the control circuit; rotation of the cam sets the instrument for control at the desired temperature.

The microswitch 20 may be used to cut off or to actuate the circuit connected thereto when the microswitch button 23 registers with the critical cam area 17; at that time the motor switch pointer 32 will have moved to register with the pointer 14 (preset by the user). Presetting of the pointer 14 thus determines the point (or degree on scale 13) at which the cam actuating area 17 is to be engaged by and thus actuate the microswitch, for control of the circuit, pursuant to the invention.

While the foregoing disclosure of exemplary embodiments is made in accordance with the Patent Statutes, it is to be understood that the invention is not limited thereto or thereby.

I claim:

1. A circuit control means comprising:

a cam member rotatable about an axis and having an axially extending undulation on a peripheral surface thereof;

a switch member having a switch actuating element engageable with said undulation, said element being of less axial dimension than said undulation;

means for relatively rotating said cam and switch member;

and selectively operable means for relatively adjusting said cam member and said element in an axial direction, in an amount greater than the axial dimensions of said element,

whereby said element ma be made to engage said undulatron in different, selecte axially spaced regions thereof,

and

means for rotating said switch member about said axis,

said switch member being mounted on said rotating means for said axial adjustment thereon relative to said cam member.

2. A circuit control means as defined in claim 1, including a bracket mounted on said rotating means, said switch member being mounted on said bracket.

3. A circuit control means as defined in claim 2 wherein said bracket is adjustable axially of said rotating means.

4. A circuit control means as defined in claim 1 wherein said switch member comprises a microswitch. 

1. A circuit control means comprising: a cam member rotatable about an axis and having an axially extending undulation on a peripheral surface thereof; a switch member having a switch actuating element engageable with said undulation, said element being of less axial dimension than said undulation; means for relatively rotating said cam and switch member; and selectively operable means for relatively adjusting said cam member and said element in an axial direction, in an amount greater than the axial dimensions of said element, whereby said element may be made to engage said undulation in different selected axially spaced regions thereof, and means for rotating said switch member about said axis, said switch member being mounted on said rotating means for said axial adjustment thereon relative to said cam member.
 2. A circuit control means as defined in claim 1, including a bracket mounted on said rotating means, said switch member being mounted on said bracket.
 3. A circuit control means as defined in claim 2 wherein said bracket is adjustable axially of said rotating means.
 4. A circuit control means as defined in claim 1 wherein said switch member comprises a microswitch. 